Research and development have been conventionally conducted on purification catalysts that do not require a noble metal as an essential component. As for exhaust gas purification catalysts, a catalyst using a perovskite composite oxide has been proposed in which the transition metal element that constitutes the composite oxide phase along with a rare earth element is partly substituted with zirconium or the like (see Patent Document 1).
Further, a catalyst containing a low-temperature oxygen occluding/releasing material and an oxygen transferring material has been proposed as a PM oxidation catalyst or an exhaust gas purification catalyst that has good oxygen occluding and releasing property at a low temperature and good sustainability of the oxygen occluding and releasing property, in which the low-temperature oxygen occluding/releasing material is made of a composite oxide with a perovskite structure and has good oxygen occluding and releasing property at a low temperature, and the oxygen transferring material is made of a composite oxide with a perovskite structure and has good oxygen transferring property (see Patent Document 2).